1. Field of the Invention
The present invention relates to an artificial disk and an insertion assembly thereof. More particularly, the present invention relates to an artificial disk which is used in a spinal fusion procedure for a spinal disease patient, and surgical instruments to insert the artificial disk easily.
2. Description of the Related Art
In general, an intervertebral disk absorbs weight and shock of a body between vertebrae except for some of the cervical spine, and serves as a buffer to disperse shock like a spring. The intervertebral disk holds the vertebrae so that the vertebrae are not dislocated, separates two vertebrae so that the spinal nerves are not pressed, broadens a range of a spinal joint pore, and allows smooth movement of each vertebra.
Such an intervertebral disk of a human being generally consists of annulus fibrosus and nucleus pulposus. The annulus fibrosus controls movement of spinal segments and 70˜80% of the inner nucleus pulposus is moisture. The intervertebral disk buffers or transmits weight or shock vertically applied. However, in a degenerative disk disease, the annulus fibrosus becomes weak in its movement and capability of containing the nucleus pulposus, and a moisture content is reduced. Accordingly, this complex result causes diseases such as spinal stenosis, osteophyte formation, disk herniation, and nerve root pressure.
One of the methods for curing diseases caused by the intervertebral disk is removing a damaged intervertebral disk from a body and replacing the disk with an artificial disk (a so-called cage) in a space between two adjacent vertebral bodies. That is, this method is to make the spine as natural as possible by implanting an artificial disk and restore an original function to the spine by restoring an original distance between two adjacent vertebral bodies, which corresponds to an original height of the intervertebral disk.
The artificial disk has an appropriate thickness and an anatomic type so that the original height of the intervertebral disk is restored, and has a hole to facilitate growth of bones afterward and a mounting part to be mounted on an insertion tool.
The transforaminal lumbar interbody fusion (TLIF), which is one of the surgical methods of inserting an artificial disk between vertebrae, is one of the spinal fusion methods, and is a surgical technique to access a disk from a posterior portion and insert an intervertebral artificial disk. That is, the TLIF is a surgical procedure in which a small incision is made along both sides of a vertebral muscle and the spine is exposed to the minimum so that a screw nail is fixed, and a spinal joint portion is removed in a direction in which a neuropore comes out and an artificial disk is inserted. The TLIF is primarily used in recent years because of less bleeding and a reduced surgery time.
In this method, in order to make a minimum incision and minimize interference in the body, one side surface S1 of a cage is inserted through a posterior portion (a back) of a body first, as shown in FIG. 7, and is placed between vertebrae, and then, a front surface F of the cage is oriented to a front side of the vertebrae (a belly of the body).
That is, an impactor which is to orient the front surface F of the inserted cage to the front side of the vertebrae, is required. The cage is placed in an appropriate position by applying a force to the opposite side surface S2 of the cage using the impactor and then rotating the cage. However, the impactor makes the surgical procedure more difficult and is controlled only by a surgeon.
A method for facilitating placement of such a cage is disclosed in Korean Patent Publication No. 10-2008-0113029. This related art has a connector of a spatula type which is curved to insert a cage which is curved to correspond to vertebrae, and a tube which is bent by a predetermined angle. Such a related art configuration is to insert the cage from a posterior portion (a back of a body) and place the cage to be oriented to a front side (a belly of a body) of the vertebrae. The aim of the TLIF is to achieve this procedure.
However, there is a problem in that the cage should be inserted in a curved form and thus an incision width becomes larger. Therefore, it is difficult to insert the cage because of the shape problem.
Also, the tube is bendable to some extent in order to place the cage to be oriented to the front side of the vertebrae, but a bendable width is not large. Even if the width is larger, the tube puts a limit to exactly placing the cage to be oriented to the front side of the vertebrae.
Therefore, the procedure greatly depends on surgeon's experience, and the impactor, which is an aid to set the location of the inserted cage exactly, is still required.